Position control system using magnetic forces for correcting the inclination of a controlled member including a torsional mounting

Claim 1

A position control system using magnetic forces for correcting the position and inclination of a controlled member relative to a reference position comprising: a first controlled member, at least a part of which is composed of a magnetic substance; a first electromagnet having at least one pole opposed to the magnetic substance of said first controlled member with a first air gap therebetween, the magnetic substance, the first air gap and the electromaget defining a electromagnet magnetic circuit; presetting means for presetting the width of the first air gap to a width greater than a predetermined width; first supporting means including at least one spring for moveably supporting said first controlled member so as to be moveable along a line of action of a first magnetic force developed between the first electromagnet and the magnetic substance; first control means coupled to said first electromagnet for controlling a control current flowing through said first electromagnet to adjust said magnetic force and to adjust the width of said first air gap so as to obtain the desired position of said first controlled member along said line of action of said first magnetic force, said magnetic circuit being saturated at a condition where said first air gap reaches said predetermined width, an elastic force developed by said spring being balanced by said first magnetic force within the elastic region of the spring at said conditon; a second controlled member, at least a part of which is composed of a magnetic substance; second supporting means comprising a torsion spring for rotatably supporting said second controlled member on said first controlled member; a correcting electromagnet having at least one pole opposed to the magnetic substance of said second controlled member at a point along a line of action of a force developed by said correcting electromagnet remote from said second supporting means and a second air gap between said correcting electromagnet and said second supporting means, the magnetic substance of said second supporting means, the second air gap and the correcting electromagnet defining a second magnetic circuit; detection means comprising a pair of interferrometers for detecting the inclination of said second controlled member relative to its position prior to the application of said first magnetic force to said first controlled member by use of two light beams; and correcting control means coupled to said correcting electromagnet and said detection means for controlling a second control current flowing through said correcting electromagnet so as to rotate said second controlled member to eliminate said inclination of said second controlled member.